Prior art conveying systems for moving bulk materials have been developed, for the most part, to provide specialized tasks depending primarily upon the path which the material is to be conveyed. For example, when transporting material continuously along relatively straight horizontal paths with gentle inclines or declines, the traditional and well-known belt conveyor system is used. When material has to be transported along steep or vertical paths, well-known conveyors such as en-masse, screw, or bucket conveyors are used. Unfortunately, when the path requires both horizontal and vertical runs, the material often has to be transferred from one conveyor system to another conveyor system that is completely different. These transfer points are very inefficient and introduce many operational problems that would not otherwise exist if only one conveyor system could be used.
The idea of conveying solids or bulk material continuously through an enclosed tube or conduit is an extremely attractive possibility. If such a system could be developed that could twist and turn in any direction and climb vertically to any elevation with unlimited length, it could render almost all prior art conveyor systems completely obsolete. But such a system does not exist in the prior art and many conveyor design engineers believe that such a system is physically impossible.
Tube conveyor systems do exist in the prior art but their performance is severely limited. For example, continuous flow pneumatic conveyors are tubular conveyors but since they operate by setting up differences in air pressure, their energy efficiency is relatively low. These systems also have relatively short maximum conveying distances. Hydraulic or slurry conveyors represent another type of tubular conveyor system. The operating principle here involves pulverizing the material to be conveyed into small particles, mixing them with a convenient liquid (such as water) and pumping the mixture through a conveying tube as a fluid by a mechanical pump. Ordinary air can also be used as the carrying fluid instead of liquid. In this case the conveyor is called an air conveyor.
The above mentioned en-masse conveyor also represents a tubular conveyor system. In this system, a series of skeletal or solid flights connected to an endless chain or other linkage, is pulled through an enclosed duct or casing which drags the material through the duct in a substantially continuous flow.
The screw conveyor represents another tubular conveying system. In this system a rotating helically shaped shaft or screw extending along the longitudinal axis of the tube forces the material to move through the tube. Although these conveyors can elevate loads, no twisting or turning is possible.
Unfortunately, all of these prior art tubular conveyor systems are very inefficient because the material is forced to move through the tube like a fluid while the walls of the tube remain stationary. Thus, the frictional forces between the tube walls and the moving material is usually very high. This friction severely limits the useful operational lengths of these conveyors and their energy consumption is extremely high.
In view of the high frictional forces that result from moving solid or bulk materials through a stationary tube, it is obvious that the only way to remove this friction is to move the tube walls along with the load. But if the conveyor is required to move the material in a continuous flow operation, the conveying tube must be some type of endless surface. Thus, in designing such a conveyor, the basic question or problem is: How can material be loaded and unloaded continuously from a moving endless tube that completely encloses the material?
Heretofore, conveyor engineers of the prior art only recognized one solution to this basic problem. This solution involved continuously splitting open and then reclosing the moving tube at the loading point and at the unloading point where material is to be inserted and taken out of the tube. This solution is apparently viewed as being the only possible solution since it appears reasonable that the only way to pass material into and out of a continuously moving endless tube that completely encloses the material is through holes that are temporarily made through the tube walls.
In order to put this prior art solution into effect, the conveying medium was constructed in the form of an endless belt with zipper-like teeth mounted continuously along each edge of the belt which mesh together. When these edges are brought opposite each other in abutting relationship and zipped together, a moving tube is formed. Consequently, the operation of slitting open and reclosing the tube so that it can be continuously loaded and unloaded is accomplished by mechanical zipper-like devices that are mounted at the loading and unloading points. This conveyor system has become known in the art as the "closed belt" conveyor. One embodiment of this closed belt tubular conveyor system is disclosed by Hashimoto in his U.S. Pat. No. 3,338,383 entitled "Pipe Conveyor" filed Sept. 21, 1965. Numerous modifications have also been disclosed. The basic idea of the closed belt conveyor was first disclosed by Henry Johns in his U.S. Pat. No. 2,013,242 entitled "Conveying Mechanism" filed May 12, 1934.
Unfortunately, there is one major flaw with the closed belt conveying system that is inherent in its basic design. It can never be removed from the system because it involves an essential mechanical operation. In particular, this flaw involves the necessity of having to continuously open and reclose the belt edges, via the zipper-like mechanism. Both edges must be exactly aligned in abutting relationship before the belt can be properly closed. This is very difficult to achieve under actual operating conditions. (For example, the opposite edges of the belt are usually under different stress conditions due to the presence of various sized objects in the closed and loaded portions of the belt.) Consequently, the zipper mechanism frequently jams, resulting in a complete shutdown of the entire conveyor system. Furthermore, since the opening and closing mechanisms are exposed to the material being inserted and removed, they operate in dusty environments. This increases mechanical wear which inevitably leads to mechanical breakdown. Thus, in many situations, the closed belt conveyor system is nice in theory but not very useful in practice.
Although numerous improvements and modifications of the closed belt conveyor system have been disclosed over the past 45 years since its introduction, the basic operating principle has remained unchanged. Evidently, conveyor engineers view the closed belt as the only possible solution to the problem of finding a viable method for continuously loading and unloading a moving endless tube. However, I have discovered a radically new and fundamentally different solution to this problem that completely eliminates having to split open and reclose the moving tube. This solution does not require any zipper-like mechanism. It is continuous flow, smooth running, almost frictionless and almost impossible to jam. It can twist and turn in any direction and can climb vertically to any elevation and its length can be extended indefinitely. Yet, the conveyor is indeed a moving tube with endless walls.